Insulated wire



Jan. 18, 1938. s, RUBEN 2,105,55-2

INSULATED WIRE Filed Sept. 3, 1932 IN VEN TOR.

ATTORNEY.

Patented Jan. 18, 1938 PATENT. ori-lcs INSULATED WIRE Samuel Ruben, New Rochelle, N. Y.. assigner to Vega Manufacturing Corporation, Wilmington. Del., a corporation of Delaware -Application September 3, 1932, Serial No. 831,654

- 4 claims.

This invention relates to insulated wires and to the composition of the insulating material thereof.

An object of the invention is to produce a 5 flexible insulated wire having a metallic covering over the insulation. Another object is to produce a flexible insulated wlre having a non-conductive metallic covering.

l Further objects will be apparent in the disclosure.

Broadly, it may be stated that the invention consists of a metal conductor, an insulating coating over said conductor and a metallic covering l over said insulation.

The metallic covering may be applied to practically all of the types of insulated wire, for instance, wire having an enamel type insulation of the spirit varnish, oil-resinous, cellulose, glyptal 20 classes,` etc., vitreous enamelled wire; rubber insulated wire; oxide-resin insulated wire; silk, paper, cotton, regenerated sheet cellulose wound or asbestos insulated wire.

The metallic covering may be applied in several 25 different ways. A low'melting point metal or alloy, such as lead-tin, may be melted and wiped on the insulated wire. Or iinely divided low melting point metal or alloy may be mixed with a carrier adapted to burn off under heat and the 30 wire may be passed through this mixture and heated to a point where the metal or alloy melts or flows and the carrier burns out, thus leaving a metallic sheath. Or a finely divided metal having a non-conductive surface, such as ilaked or powdered aluminum may be mixed with a resinous or other type carrier, and baked on the insulated wire.

A particularly useful metallic coated wire of this type may consist of an insulated conductor 4o of the type described in my copending application: 580,531 of 12th December, 1931, and Patents numbered 1,896,043, 1,896,041 and 1,896,042 issued January 31st, 1933, with a coating of finely divided aluminum and a Water insoluble resinous 45 binding material. The insulated wire may be prepared as follows: An oleoresinous varnish consisting of ester and kauri gums, China-wood and linseed oil, turpentine and mineral thinner, is first made up by heating these materials t0- 50 gether, in proper proportion, to 500 F. A further compound consisting of one part Chinawood oil, one part fish oil and one part phenolformaldehyderesin is then made up by heating these three materials together at 450 F. for ilf- 55 teen minutes. Three parts of this latter com- (cl. 11a-zw pound are added to seven parts of the ester-kauri gum compound, thus, producing a varnish of good quality for the purposes of this invention. 400 cc. of this varnish are ground with 200 grams of a nely divided refractory material, preferably, 5 an oxide such as iron oxide and after the mixture has been thoroughly groundso that the oxide particles have been reduced to a very line dimension, the compound is applied to the wire.

y In some instances it is desirable to add and grind in an inorganic high temperature binder material, suchI as boric acid, to the insulating compound to obtain adhesion at high temperatures. The use of this borate or inorganic binder is set out in my copending cases heretofore menvtloned. Preferably, this inorganic binder should have a meltingor iluxing point below the carbonization point of the organic materials used in the coating.

In insulating this wire, a continuous-coating process is used, the wire passing through cups containing the insulating compound and being heated and baked in ovens located between the cups. If necessary, the compound may be thinned out with suitable solvent thinners such as naphtha, xylol, toluol, etc.

The thickness of the coating may be the standard thickness set by the American Engineering Standards Committee for enamel insulated wire or may be less or greater, depending upon the flexibility, dielectric strength, abrasion resistance, etc., required. Likewise, the amount of refractory material, such as the oxide, may be determined by the degree of heat 'resistance necessary. Generally, it may be stated that the amount of refractory $5 material should be such that after the wire has been wound into coils, it will afford a non-conductive spacer between turns even though the dielectric organic carrier or binder, such as varnish, should become carbonized or burn out. 40

In preparing the metallic covering I may use materials ln the following proportion: to 400 cc. of the phenol-oil varnish hereinabove described, I add 100 grams of flaked or finely divided aluminum. This aluminum is non-conductive,

probably due to the thin film of oxide which seems to naturally form upon the surface and the thickness of this insulating iilm can be materially increased by chemical treatment, as for instance,

by immersion in nitric acid. A thin smooth coating of the aluminum varnish is applied Vto the wire in a manner similar to the application of the oxide-varnish, the insulated wire passing through cups containing the aluminum varnish compound and being baked on in ovens located between the 5I cups. If desirable an inorganic binder, such as boric acid, may be added to the aluminum varnish.

It will be found that metallic insulated wire of this type is resistant to harmful corona eects and when the metal is properly applied a dense, flexible, abrasion-resistant, Water and fire proof coating is had.

To illustrate the invention, reference is made to the drawing.

In the figure the wire (i) has an insulating coating 2) consisting of finely divided iron oxide, held upon the wire by a dielectric resinous binder and has an outer coating (3) consisting of a baked on aluminum varnish mixture. It is understood that the insulating coating (2) might consist of rubber, or an enamel type varnish as described instead of oxide-resin.

The metallic coatings illustrated may be applied to any of the types of insulated wire in use or hereinabove described. In the claims the terms insulation, insulated and "non-conductive are used in relation to electricity.

I claim:

1. A wire having an inner insulation coating including finely divided iron oxide and having an outer coating comprising finely divided aluminum held on said insulated wire by a water insoluble binder.

2. An insulated wire having an inner insulation coating containing finely divided particles oi iron oxide and an outer non-conductive coating over its insulation coating consisting substantially of finely divided aluminum, a binder and a boron compound.

3. A wire having an insulation containing a flnely divided refractory oxide material, an organic binder, an inorganic binder compound and having an outer non-conductive coating comprising finely divided aluminum held on said insulated wire by a water-insoluble binder.

4. A wire having an insulation containing a finely divided refractory oxide material, a boron compound, and organic binding material, and a non-conductive coating of finely divided aluminum held on said insulated wire by a waterinsoluble binder.

SAMUEL RUBEN. 

